Floating piston for selective hydraulic packer

ABSTRACT

A well packer of the type which is set by hydraulic pressure injected through the tubing string, having a setting chamber between the pistons therein which actuate the packer, wherein one of the pistons is floating while the packer is being lowered to compensate for thermal expansion or contraction and pressure differentials encountered as the packer is lowered in the well in order to prevent undue pressure from being applied to the pistons which could cause the shearing of shear pins holding the packer in unset position which would prematurely set the packer.

May 8, 1973 United States Patent 1191 Douglas FLOATING PISTON FORSELECTIVE HYDRAULIC PACKER Primary Examiner-James A. LeppinkAttorney-Robert W. Mayer, Thomas P. Hubbard, Jr., Daniel Rubin, RaymondT. Majesko, William E. John- [75] Inventor: Bobby L. Douglas, Dallas,Tex.

[73] Assignee: Dresser Industries, Inc., Dallas, Tex. son, Jr., MorganL. Crow, Eddie E. Scott and Howard M Filed: May 24, 1971 Om Appl. No.:146,027

ABSTRACT A well packer of the type which is set by hydraulic 521 US. p sinjected thmugh the tubing String, having a 51 int. c1. 23/04 chamberPistons "3 Which tuate the packer, wherein one of the pistons 18floating [58] Field ofSearch......................166/120,121,122,

166/212 while the packer is being lowered to compensate for thermalexpansion or contraction and pressure differentials encountered as thepacker is lowered in the [5 6] References Cited well in order to preventundue pressure from being ap- UNITED STATES PATENTS plied to the pistonswhich could cause the shearing of shear pins holding the packer in unsetposition which would prematurely set the packer.

3,122,205 2/1964 Brown et al. .........................166/l20 3,361,2071/1968 3,460,616 8/1969 Chenoweth ..........................166/120Tucker et al. ........................166/120 12 Claims, 10 DrawingFigures 4 Sheets-Sheet l w a mm ID a 5 a 0 a Z a 6 5 U m ur ww a xx 2 mm3 A r A w 0 4 7 a 5 m m r T.

ATTOP/VEY Patented Ma 8, 1913 Patented May 8, 1973 4 Sheets-Sheet 2 fig.E

INVENTOP 50/55) L DOUGLAS M 7mm ATTO Q/VE) Patented May 8, 1973 4Sheets-Sheet 5 ATTOPNE) Patented May 8, 1973 3,731,740

4 Sheets-Sheet 4.

//v van/rap 50515) L. DOUGLAS ATTORNEY FLOATING PISTON FOR SELECTIVEHYDRAULIC PACKER BACKGROUND OF INVENTION The improvement comprehended bythis invention is applicable to a hydraulic packer of the type disclosedin United States Letters Patent No. 3,460,616, entitled RetrievablePacker with which is employed slips or gripping members like thatdisclosed in United States Letters Patent No. 3,548,936 entitled WellTools and cient extent to break shear pins which maintain the packer inunset condition, thereby causing premature setting of the packer.

The improvement comprehended by this invention is intended to overcomesuch problem.

SUMMARY OF THE INVENTION Although hydraulic packers of the type to whichthis improvement is addressed could be adapted for use in multistringinstallations, it is particularly useful in wells having more than oneproducing zone wherein the operator might desire to produce and depleteone zone at a time. In such an installation the operator could use onestring of tubing with the packer between each zone and with a valvecapable of being open to communicate with the producing zone below eachpacker. Thus, the operator would have the capability to produce from anyselected zone by opening the valve in the tubing string communicatingwith such zone below the packer set thereabove, leaving the other valvesin the string closed.

In such selective zone completion the packers are lowered into the wellas the tubing string is made up. When the complete tubing string orstrings are positioned in the well bore the packer, as an example, maybe successively set and tested for leaks after they are set. This iscarried out by closing the lower end of the tubing string by a floatingball valve. A frangible plug closes communication between the tubingbore and a setting chamber between the pistons in the packer. A shiftingsleeve in the tubing bore is arranged to shear the frangible plug whenmoved upwardly or downwardly as the case may be, to open the porttherein and allow communication between the bore of the tubing stringand the setting chamber to permit fluid pressure to be applied to thesetting chamber and the setting piston therein to set the packer in themanner which will be hereinafter described.

After the packer is set the sleeve valve below the packer in the tubingstring is opened and pressure may be applied to either the casingannulus or inside the tubing string to test the packer to determinewhether or not it will hold pressure.

After setting and testing the lowermost packer in the tubing string thenext lowest packer may likewise be set and tested with all valves in thetubing string between the packers closed except that immediately belowthe packer being set and tested. Selected packers in the string maylikewise be set and tested.

Prior to running the packer in the well the isolated setting chamberbetween the pistons in the packer is filled with fluid through portsprovided through the wall of the chamber and the ports are then closed.Thereby the setting chamber between the pistons is filled with fluidwhich is isolated from the fluid exter nally thereof and fluid in thetubing string by reason of the shearable plug in the shifting sleeve andthe seals on the pistons. At least one of the pistons is movablelongitudinally of the chamber to sufficient extent to compensate forexpansion or contraction of the fluid in the setting chamber by reasonof temperature changes outside same or by reason of equalization ofpressure differential between fluids outside and inside the chamber, sothat such expansion or pressure change will not be transferred throughthe setting sleeve to the shearable elements in the packer to causepremature setting of the packer.

It is therefore, a primary object of the invention to provide means in ahydraulic packer to compensate for temperature and/or pressure changesencountered upon lowering the packer in the well to prevent prematuresetting of the packer.

Another object of the invention is to provide a setting chamber betweenthe pistons in a hydraulic packer which is isolated from fluids insideand outside the chamber, which chamber is filled with fluid and whereinat least one of the pistons is movable to compensate for expansion orcontraction of the fluid therein by reason of temperature changes and tocompensate for changes in pressure differential between the fluid in thechamber and fluid outside the chamber to thereby prevent such forcesfrom being transferred to shearable members in the packer to causepremature setting of the packer.

A further object of the invention is to provide in a hydraulic packer anisolated setting chamber between the pistons therein which is filledwith fluid and communication between the chamber and the tubing stringmay be established through a shearable plug actuated by a shiftingsleeve from inside the tubing string.

Still another object of the invention is to provide a plurality of suchhydraulic packers in a tubing string, each having an isolated settingchamber therein filled with fluid wherein each such chamber may beselectively placed in communication with the tubing string by means of ashifting sleeve which establishes communication between the tubingstring and the setting chamber by a shearable plug which provides apositive seal and isolation of said chamber from the tubing string untilthe shearable plug is broken to establish communication between the boreof the tubing and the chamber.

A general object of the invention is to provide an improvement in ahydraulic packer which positively prevents premature setting of thepacker while being lowered in the well by reason of pressure andtemperature variations.

Other and further objects of the invention will become apparent uponreading the detailed specification hereinafter following and byreferring to the drawings annexed hereto.

DESCRIPTION OF DRAWINGS A suitable embodiment of the invention is shownin the attached drawings, wherein,

FIGS. 1,2, 3 and 6 is partially sectionalized elevational view of ahydraulic packer in unset condition incorporating the improvementsdisclosed and claimed herein;

FIG. 4 is a transverse sectional view taken on the line 4-4 of FIG. 3.

FIG. is an enlarged vertical sectional view of the shear plug throughwhich communication is established between the bore of the tubing stringand the setting chamber when it is sheared; and

FIGS. 7-10, inclusive, is a partially sectionalized elevational view ofthe packer in set position.

DESCRIPTION OF A PREFERRED EMBODIMENT Numeral references are employed toindicate the various parts shown in the drawings and like numeralsindicate like parts throughout the various figures of the I drawings.

The number 1 indicates a top connection for the packer which is adaptedto be threadedly engaged to a tubing string extending into the wellcasing.

The upper slip control housing 2 is threadedly engaged to the packerconnection 1, and has positioned therein a spacer ring 3 which ispositioned between the slip carrier 7 and the end of the top connection1.

The split retainer ring 4 is interlocked with a groove extending aboutthe upper end of the slip carrier 7, and provides an upper abutment forthe slip control spring 5, which is the subject of the co-pendingapplication of Andrew J. Tucker entitled Resilient Slip Suspension Meansin Hydraulic Packer, Ser. No. 146,056 filed concurrently herewith.

The cap 6 which acts as a retrieving head when the packer is disengaged,is threadedly engaged to the lower end of the slip control housing 2 andthe slip carrier 7 slidably extends therethrough.

The tubular slip carrier 7 provides a support for the upper slip 8. Theslip carrier 7 has spaced shoulders 7a and 7b thereon providing arecessed area therebetween about which the slip 8 is suspended toprevent an internal bind on the slip when it is in set position.

A flat spring 9 is secured to the body of slip 8 by means of a suitablecap screw 10. The inner end of the spring 9 is biased against the slipcarrier 7 and the slip 8 is suspended on the lug 8e provided on the slipcarrier 7 in contact with shoulder 8f on the slip body to maintain theslip in vertical position. The slip 8 is of the type disclosed in U. S.Pat. No. 3,548,936 which may be tilted with reference to the slipcarrier 7 when force is exerted against the end thereof as disclosed insaid patent.

The slip 8 has teeth 80 and 81) on the outer surface at opposite endsthereof for movement into anchoring engagement with the well casing. Anelongated slot 8c is provided in the wall of the slip carrier 7 throughwhich extends a slip suspension pin 8d which is secured to the slip bodyso that upon the tilting and setting of the slip same can pivot aboutthe pin 8d and move upwardly in the slot 80 to compensate for verticalmovement thereof.

The upper mandrel 11 is threadedly engaged to the top connection 1 andextends through the upper portion of the packer and provides a flowpassage therethrough.

The upper head of the packer assembly includes a cap 12 threadedlyengaged to the upper end of the balance valve chamber 19. An annularspace 12a is provided between the cap 12 and mandrel 11 for fluidcommunication with the upper end of the balanced piston 13. The balancepiston 13 is slidably disposed in the balance chamber 19 and has seals14 and 15 on the inner and outer sides thereof which seal between sameand the outer surface of the mandrel 11 and the inner surface of thebalance chamber 19. Fluid communication ports are provided through thewall of the balanced chamber 19 and communicate with the area thereinbelow the balance valve 18 and with the ports 27a to equalize pressureacross the packer seals when the valve is open. The balance valve 18 hasa seal 18a thereabout which seals against the inner wall of the balancechamber 19. The balance valve 18 is suspended to the mandrel 11 by meansof a keeper ring 17 which is secured thereto by means of a retainer ring16 and is positioned in a slot extending about the mandrel 11.

The balance valve subseal assembly 20 includes an outer shell whichrests upon a shoulder 22a provided interiorally of the seal housing 22and a seal 20b is provided between same and the inner surface of theseal housing 22. An elongated seal 20a is provided on the inner surfaceof the seal housing 20 which is spaced from the outer surface of themandrel 11 so that it can receive the lower end of the balance valve 18to isolate the area in the casing above and below the packer sleeves 25aand 25b when expanded.

The seal housing 22 is attached at its upper end to the balance valvechamber 19 and at its lower end to the upper packer rubber supportthimble 24. The seal housing 22 is threadedly attached to the upper endof the packer body 25 and a .seal 23 is provided therebetween.

The resilient packer seals 25a and 25b are slidably disposed about thepacker body 25 between the upper thimble 24 and the lower thimble 24aand are spaced apart by a spacer member 26. The lower thimble 24a isattached to a spacer collar 27 and is suspended to a shoulder 250 on thelower end of the packer body 25 so that it is slidably disposed withrelation to the packer body. Ports 270 are provided through the wall ofthe spacer collar 27 to provide communication between the areas aboveand below the packer seals 25a and 25b when valve 19 is open to provideequalization of pressurethereacross before retrieval.

A floating piston 28 is movable in the setting cylinder 38 and has seals29 and 29a on the outer and inner sidesthereof, respectively, which sealbetween the inner surface of the setting cylinder 38 and the outersurface of the mandrel l I. A shoulder 29b on the piston 28 is spacedfrom shoulder 29c at the lower end of the spacer collar 27 so as topermit limited upward movement of the piston 28 in response to fluidexpansion or pressure increase of fluid in the setting chamber, whichwill be hereinafter described.

A threaded hole 29d is provided on the exterior surface of the piston 28which is accessible through a passage 292 through the wall of thesetting cylinder 38 through which a screw may be inserted for temporaryretention of the setting cylinder 28 in fixed position while the settingchamber 38 is being filled with fluid as hereinafter described.

Removable pressure plugs and 300 are provided in threaded passagesthrough the wall of the setting cylinder 38 so that upon removal of theplugs 30 and 30a suitable fluid supply circulating connections (notshown) may be attached in said passages through which fluid may beinjected for filling the setting chamber A with a suitable fluid. Thefluid may be either an incompressible liquid such as a relatively lightoil or a gas such as freon or nitrogen.

A mandrel sub 31 is threadedly engaged to the lower end of the uppermandrel 11 and is threadedly engaged at its lower end to the shiftingsleeve housing 37. A seal 33 is provided between the mandrel sub 31 andthe upper end of the shifting sleeve housing 37.

A shifting sleeve 32 is slidably disposed within the housing 37 and isretained in place therein by means of a shear plug 34 which isthreadedly engaged in the wall of the shifting sleeve housing 37 and hasan outer end thereon which extends into a channel 32a formed about theupper end of the shifting sleeve 32. The shear plug 34 has a centralpassage 34a therein which communicates with the chamber A and is closedat its outer end by the shearable extension of the shear plug 34. Ports32c are provided through the wall of the shifting sleeve 32 which may bebrought into alignment with ports 340 through shear plug 34 upon theshearing of the shear plug in the manner hereinafter described. Anannular shoulder 32b is provided interiorally of the shifting sleeve 32for engagement with a shifting tool lowered from the surface for upwardmovement of the shifting sleeve 32 to break the shear plug 34 to therebymove the ports 32c into position with the passages 34a such that fluidcommunication is established between the bore of the mandrel 11 and thechamber A. A suitable seal 35 (FIG. 5) is provided between the shearplug 34 and a shoulder in the passage through which it extends toprevent fluid leakage thereabout.

Segmented cylinder locks 36 are suspended about the shifting sleevehousing 37 and are arranged to move inwardly by reason of a shoulder 36athereon which extends into a recess 37a provided about the housing 37.The lower end of the cylinder lock 36 has an enlarged portion thereonwhich extends into a recess 38a provided in the setting cylinder 38 andis retained in outward position in said recess by the extension 390 onthe upper end of the setting sleeve 39, but is permitted to moveinwardly out of the recess 38a when the sleeve 39 moves downward todisengage the extension 390 therefrom to thereby permit relativemovement between setting sleeve 39 and the setting cylinder 38 upon thesetting of the packer.

The setting sleeve 39 comprises a piston which is slidably and sealinglyengaged with the inner wall of the setting cylinder 38 and the outerwall of the lower mandrel 47 by seal members 39a and 39b.

The cylinder slip housing 40 extends about the setting sleeve 39 and isthreadedly engaged to the setting cylinder 38. The segmented cylinderslips 41 have teeth 41a on the inner side thereof which are urged intoengagement with the outer surface of the setting sleeve 39 by means ofslip springs 42 which extend into bores 41b provided in the lower end ofthe slips 41a and are attached to slip guides 43 mounted upon the upperend of the shear housing 45.

The shear pins 44 frangibly attach the shear housing 45 to the settingsleeve 39.

The cap 46, threadedly engaged to the lower end of the setting sleeve 39provides a lower head for the packer assembly which is engageable withthe upper end of the lower slip 49 to set same upon the setting of thepacker.

The lower mandrel 47 is threadedly engaged to the shifting sleevehousing 37 and to the bottom connection 55. The slip 49 is pivotallymounted on the lead-in sleeve 48, said lead-in sleeve 48 having arecessed surface 48a against which the spring 49c is engaged to bias theslip 49 to vertical position and maintain same out of engagement withthe casing until actuated in the manner hereinafter described. The slip49 is of the same type as upper slip 8 and functions in similar manner.It has upper and lower outer teeth 49a and 49b thereon arranged toengage the casing wall to anchor same thereagainst.

The slip 49 is pivotally mounted on a pin 49e which extends through anelongated passage 49f and is engaged with the sleeve 48 which permitsthe slip to pivot about said pin to set position, as shown in FIG. 10,when pressure is exerted against the upper end thereof by the lower head46.

The sleeve 48 on which the slip 49 is mounted extends into the slipcontrol housing 50, is secured thereto by the shearable set screws 50aand is spaced from the lower end thereof by a resilient take-up ring50b. The slip control housing 50 is threadedly engaged to the mandrelshear housing 51 which in turn is frangibly connected to bottomconnection 55 by the shear pins 52.

Segmented mandrel slips 53 have teeth on the inner sides thereofengageable with the outer surface of the bottom connection 55 and areseated in the mandrel housing 54 which in turn is suspended to the lowerend of the shear housing 51 and is arranged to come into engagement withthe teeth 55a on the bottom connection 55 when the shear pin 52 issheared for retrievai of the packer.

A stop ring 5 is arranged to engage the lower end of the mandrel sliphousing 54 upon shearing of the shear pin 52 and the movement of themandrel upwardly therein in order to retrieve the slip control housing50 with the packer.

OPERATION AND FUNCTION The packer is assembled in unset condition asshown in FIGS. 1-6 inclusive. Prior to attaching same to the tubingstring and running it into the well, an incom pressible fluid or gas isinjected through the ports 30-30aby a suitable fluid dispensing deviceto fill the chamber A with such fluid. While it is being filled a screwis inserted in the threaded hold 29d through the passage 29c to retainthe piston 28 in the position shown in FIG. 3. After filling the chamberA the passages 30 and 30a are closed by suitable plugs to retain thefluid therein, and the screw is removed from the threaded hole 29d.

The packer is then attached in the tubing string and lowered into thewell to the desired level for setting. While it is being lowered anychanges in temperature or pressure differential between the chamber Aand exteriorally of the tool above or below the pistons 28 and 39 iscompensated for by expansion or contraction of the fluid in the chamberA. Such is permitted by floating piston 28 which may float betweenshoulder 29b and 29c.

When the packer has reached the desired level for setting the bore ofthe tubing is closed below the packer by a conventional ball valve and aconventional setting tool (not shown). is run into the tubing and thedogs thereon engage with the shoulder 32b on the shifting sleeve 32.Upward pull on the setting tool 32 shears the end off of the frangibleplug 34 and upon further upward movement the ports 32c come intoposition with the passages 34a such that fluid communication isestablished between the bore of the tubing string and the chamber A.Upon exertion of fluid pressure from the tubing through passage 34a intochamber A downward force is exerted on the piston 39 and an upward forceon the setting'cylinder 38 thereby shearing the shear pin 44, allowingthe setting cylinder 38 to move upwardly to compress and expand thepacking rubbers 25a and 25b. Such movement causes the upper head 12 tocome into contact with the lower end of upper slip 8 and move same toset position against the casing wall to anchor same and stop furtherupward movement of upper head 12 and expands packer rubbers 25a and 25b.The downward movement of the piston 39 causes the lower head 46 to comeinto contact with the upper end of the slip 49 and move same into setposition. The slip teeth 41a engage the piston 39 and retain it in downposition. The downward movement of piston 39 disengages the lockingmembers 36 from the cylinder 38 to permit upward movement of settingcylinder 38 as the packer is set.

To disengage the packer an upward pull is exerted on the tubing stringto shear the lower shear pin 52 and allow the slip control housing 50 tomove upwardly to disengage the lower slip 49 and permit the packet torelax to running in position so that it can be retrieved from the well.

Having described my invention, 1 claim:

1. In a fluid pressure actuated retrievable packer assembly, thecombination of:

A tubular support for the packer assembly; a packer body surrounding thesupport; at least one resilient packer sleeve slidably mounted on thepacker body; a tubular cylinder surrounding the support below the packersleeve; a tubular member surrounding the support above the packersleeve;

upper and lower pistons positioned in the spacev between the cylinderand the support, and being in sealing engagement with the cylinder andthe support providing a chamber between said pistons; eloseable portmeans through the wall of the cylinder through which the chamber may befilled with fluid; a passage through the wall of the support arranged tocommunicate with the chamber; frangible means closing said passage; andmovable means positioned inside the tubular support, engaged with thefrangible means; said movable means being engageable with a tool loweredfrom the surface to break the frangible means to provide communicationbetween the chamber and the interior of the tubular support.

2. The combination called for in claim 1 wherein the lower piston isconnected to the cylinder by a shearable member whereby when saidshearable member is broken by pressure exerted in the chamber againstthe piston the cylinder moves upwardly in relation to the piston to movethe resilient packer sleeve and the upper tubular member upwardly, andthe lower piston moves downwardly; and upper and lower slip meanssurrounding the support above and below the packer assembly, the upperslip being engageable with upper tubular member and the lower slip beingengageable with the lower piston to anchor the slips and expand thepacker sleeve against a surrounding well casing.

3. The combination called for in claim 1 wherein the upper piston ismovable longitudinally of the chamber in response to variations oftemperature and pressure exerted on fluid within the chamber.

4. The combination called for in claim 1 wherein the upper tubularmember is a balance valve housing having a balance valve thereinarranged to be opened and closed by movement of the upper tubularmember.

5. The combination called for in claim 1 wherein the means to break thefrangible means is a sleeve slidably disposed in the tubular supportengaged with the frangible means said sleeve having a shoulder thereinengageable with a tool extending from the surface, and having a portthrough the wall thereof arranged to be aligned with the passage uponbreaking the frangible means and movement of said sleeve upwardly.

6. In a fluid pressure actuated retrievable packer assembly of the typesuspended to a tubing string and having pistons therein which whensubjected to pressure from interiorally of the tubing causes a packersleeve support cylinder thereabout to move with relation to the pistonsto expand the packer, the improvement comprising, a chamber between thepistons filled with a fluid, one of said pistons floating and being freeto move longitudinally of the chamber in response toexpansion orcontraction of the fluid.

7. The combination called for in claim 6 with the addition of closeableport means through the wall of the chamber to permit the filling of saidchamber with fluid.

8. The combination called for in claim 6 with the addition of passagemeans adapted to establish communication between the chamber and theinterior of the tubing; frangible means closing said passage means; andmeans to break the frangible passage means from interiorally of thetubing to establish communication between the tubing and the chamber.

9. The combination called for in claim 8 with the addition of shearablemeans connecting the cylinder to the other said piston whereby uponbreaking the frangible means pressure may be injected into the chamberfrom the tubing through the passage means to break the shearable meansand disengage the cylinder fromthe piston to allow relative movementtherebetween. 10. The combination called for in claim 9 with theaddition of anchor means on the tubing above and below the packerassembly expandable by engagement with ends of the packer assembly uponrelative movement between the cylinder and piston.

11. The combination called for in claim 7 with the the addition of meansto disengageably attach the movable piston to the cylinder while thechamber is being filled with fluid.

12. in a fluid pressure actuated packer assembly having a piston thereinwhich when subjected to pressure from interiorally of the tubing causesa packer sleeve support cylinder thereabout to move with relation to thepiston to expand the packer, the improvement comprising, a chamberadjacent the piston filled with a fluid, said piston floating and beingfree to move longitudinally of the chamber in response to expansion orcontraction of the fluid.

1. In a fluid pressure actuated retrievable packer assembly, thecombination of: A tubular support for the packer assembly; a packer bodysurrounding the support; at least one resilient packer sleeve slidablymounted on the packer body; a tubular cylinder surrounding the supportbelow the packer sleeve; a tubular member surrounding the support abovethe packer sleeve; upper and lower pistons positioned in the spacebetween the cylinder and the support, and being in sealing engagementwith the cylinder and the support providing a chamber between saidpistons; closeable port means through the wall of the cylinder throughwhich the chamber may be filled with fluid; a passage through the wallof the support arranged to communicate with the chamber; frangible meansclOsing said passage; and movable means positioned inside the tubularsupport, engaged with the frangible means; said movable means beingengageable with a tool lowered from the surface to break the frangiblemeans to provide communication between the chamber and the interior ofthe tubular support.
 2. The combination called for in claim 1 whereinthe lower piston is connected to the cylinder by a shearable memberwhereby when said shearable member is broken by pressure exerted in thechamber against the piston the cylinder moves upwardly in relation tothe piston to move the resilient packer sleeve and the upper tubularmember upwardly, and the lower piston moves downwardly; and upper andlower slip means surrounding the support above and below the packerassembly, the upper slip being engageable with upper tubular member andthe lower slip being engageable with the lower piston to anchor theslips and expand the packer sleeve against a surrounding well casing. 3.The combination called for in claim 1 wherein the upper piston ismovable longitudinally of the chamber in response to variations oftemperature and pressure exerted on fluid within the chamber.
 4. Thecombination called for in claim 1 wherein the upper tubular member is abalance valve housing having a balance valve therein arranged to beopened and closed by movement of the upper tubular member.
 5. Thecombination called for in claim 1 wherein the means to break thefrangible means is a sleeve slidably disposed in the tubular supportengaged with the frangible means said sleeve having a shoulder thereinengageable with a tool extending from the surface, and having a portthrough the wall thereof arranged to be aligned with the passage uponbreaking the frangible means and movement of said sleeve upwardly.
 6. Ina fluid pressure actuated retrievable packer assembly of the typesuspended to a tubing string and having pistons therein which whensubjected to pressure from interiorally of the tubing causes a packersleeve support cylinder thereabout to move with relation to the pistonsto expand the packer, the improvement comprising, a chamber between thepistons filled with a fluid, one of said pistons floating and being freeto move longitudinally of the chamber in response to expansion orcontraction of the fluid.
 7. The combination called for in claim 6 withthe addition of closeable port means through the wall of the chamber topermit the filling of said chamber with fluid.
 8. The combination calledfor in claim 6 with the addition of passage means adapted to establishcommunication between the chamber and the interior of the tubing;frangible means closing said passage means; and means to break thefrangible passage means from interiorally of the tubing to establishcommunication between the tubing and the chamber.
 9. The combinationcalled for in claim 8 with the addition of shearable means connectingthe cylinder to the other said piston whereby upon breaking thefrangible means pressure may be injected into the chamber from thetubing through the passage means to break the shearable means anddisengage the cylinder from the piston to allow relative movementtherebetween.
 10. The combination called for in claim 9 with theaddition of anchor means on the tubing above and below the packerassembly expandable by engagement with ends of the packer assembly uponrelative movement between the cylinder and piston.
 11. The combinationcalled for in claim 7 with the the addition of means to disengageablyattach the movable piston to the cylinder while the chamber is beingfilled with fluid.
 12. In a fluid pressure actuated packer assemblyhaving a piston therein which when subjected to pressure frominteriorally of the tubing causes a packer sleeve support cylinderthereabout to move with relation to the piston to expand the packer, theimprovement comprising, a chamber adjacent the piston filled with afluid, said piston floating and being free to move longitudinally of thechamBer in response to expansion or contraction of the fluid.